Edmund B. Fitzgerald, chairman of the Baseball Owners' Labor Relations Committee, said today that a new contract with the players' union would have been difficult to obtain if the sale of three Oakland A's players last summer had not been cancelled.

Testifying in U.S. District Court in a suit brought by A's owner Charles O. Finley against baseball commissioner Bowie Kuhn acted in the best interest of the game by vetoing the sales.

Fitzgerald, also board chairman of the Milwaukee Brewers and a member of baseball's executive council, had support on that point from fellow council members John J. McHale of the Montreal Expos and John E. Fetzer of the Detroit Tigers. They supported the defense's contention that Kuhn had the authority to disapprove the sales and did so in good faith.

After an arbitrator created a free agent system that was upheld by the "stringent re-entry draft system" for unsigned free agents to preserve competitive balance among the clubs, Fitzgerald said.

If the $3.5 million sales of Vida Blue to the New York Yankees and Rollie Fingers and Joe Rudi to the Boston Red Sox had been allowed to stand, Fitzgerald said, the wealthier clubs would have snapped up the superstars. Instead, a system was established in which the lower-ranking clubs got first shot at the new free agents last fall, although their prices were still high.

"I club foresee Marving Miller coming to us and saying, 'Here you have a relationship between the three clubs - Oakland, New York and Boston - and you have no restraints as far as selling among the contending clubs,'" Fitzgerald said of the executive director of the players' union.

"And then, he'd turn to us and say, 'Why do we have to have restraints when the rights of my players are involved?'"

In essence, Fitzgerald said, Miller would contend the players should not be forced to negotiate with the allegedly weaker and less affluent clubs while the owners exercised carte blanche among themselves. The players might not have agreed to a re-entry draft in the new contract - signed after the Finley deal - if the sales had stood, he said.